Percentage Calculator
Quickly calculate percentages, percentage increases, percentage decreases and percentage differences with a clean web calculator inspired by SUMX.
Work out a percentage
Four ways to calculate. Results update as you type, and nothing you enter leaves your browser.
What is X% of Y?
30
20% of 150 is 30.
150 × 20 ÷ 100 = 30
Percentage increase or decrease
20% increase
150 to 180 is a 20% increase.
(180 − 150) ÷ 150 × 100 = 20%
Add or subtract a percentage
180
150 plus 20% is 180.
150 × (1 + 20 ÷ 100) = 180
Need percentages on your phone?
SUMX includes percentage, VAT and discount tools inside a clean everyday calculator for Android, with history, favourites and more available with SUMX Pro.
How to calculate a percentage
To find X% of a number, divide the percentage by 100 and multiply it by the number.
20% of 150 = 20 ÷ 100 × 150 = 30
How to calculate percentage increase
Subtract the original value from the new value, divide by the original value, then multiply by 100.
150 to 180 = (180 − 150) ÷ 150 × 100 = 20% increase
How to calculate percentage decrease
The calculation is identical. A negative result simply means the value went down, and the minus sign is dropped when the change is described in words.
200 to 150 = (150 − 200) ÷ 200 × 100 = −25%, so it is a 25% decrease
Common percentage examples
| Calculation | Result |
|---|---|
| 10% of 50 | 5 |
| 20% of 150 | 30 |
| 25% of 80 | 20 |
| 50% of 90 | 45 |
| 150 increased by 20% | 180 |
| 200 reduced by 25% | 150 |
Percentage questions
- What is a percentage?
- A percentage is a number expressed as a fraction of 100. For example, 25% means 25 out of 100.
- How do I calculate 20% of a number?
- Divide 20 by 100, then multiply by the number. For example, 20% of 150 is 30.
- How do I calculate percentage increase?
- Subtract the original value from the new value, divide by the original value, then multiply by 100.
- How do I calculate percentage decrease?
- Subtract the original value from the new value, divide by the original value, then multiply by 100. A negative result means a decrease.
- Does SUMX include percentage tools?
- Yes. SUMX includes a percentage tool alongside VAT, discount and other calculator features.
More SUMX tools: the VAT calculator for adding and removing VAT, the discount calculator for sale prices and savings,, the markup & margin calculator for pricing and profit, the unit converter for length, weight and temperature, and the currency converter for exchange rates. If you need a hand with SUMX, the support pages cover getting started, history and troubleshooting. This calculator runs entirely in your browser and sends nothing anywhere; the privacy policy explains how the rest of the site behaves.